Abstract : The energy densities required to produce ophthalmoscopically visible retinal burns in the periphery of the fundus were determined for six human Caucasian subjects. The thresholds for retinal burns in humans were significantly higher than those required to produce similar lesions in monkey or rabbit eyes and is probably related to the differential pigmentation and image size in the retinas of these species. Using a 3 degree spot size, the theoretical energy necessary to produce a visible burn in brown-eyed subjects was 4.5 cal/sq cm for a 1 sec. exposure. Exposure durations shorter than 1 sec. required less overall energy while those over 1 sec. required more. Threshold energies for two blue-eyed patients were significantly higher than those for brown-eyed patients and may also be related to the degree of pigmentation of the RPE. Functional studies of a macular burn case is reported. (Author)